Early in the interview Kandel remembers being run out of his native Austria by the Nazis:

How old were you when the Nazis marched into Vienna?

I was 8 ½. Immediately, we saw that our lives were in danger. We were completely abandoned by our non-Jewish friends and neighbors. No one spoke to me in school. One boy walked up to me and said, “My father said I’m not to speak to you anymore.” When we went to the park, we were roughed up. Then, on Nov. 9, 1938, Kristallnacht, we were booted out of our apartment, which was looted. We knew we had to get out.

Fortunately, my mother had the foresight to apply for visas to the United States earlier. For more than a year, we waited in the terror of Vienna for our immigration quota number to come up. When it finally did, my older brother, Ludwig, and I made the Atlantic crossing alone. Our parents came later. On the trip, it’s amazing how unfrightened I was, considering that even before the Nazis, I was an apprehensive child. You rise to the occasion.

Q: As neuroscience moves forward, there are all kinds of new possibilities emerging. There are people who are experimenting with ways to erase unpleasant memories. Do you approve?

A: I have no difficulty about enhancing memory. Removing memory is more complicated. If it’s to reduce the impact of a particular trauma, I have no difficulty with that, but there are other ways to deal with it — cognitive behavior therapy, exposure therapy, drugs. To go into your head and pluck out a memory of an unfortunate love experience, that’s a bad idea.

You know, in the end, we are who we are. We’re all part of what we’ve experienced. Would I have liked to have had the Viennese experience removed from me? No! And it was horrible. But it shapes you.

As Jonah* notes in his piece, this is the problem we’ll encounter if (Jonah says when) we figure out how to remove specific memories: How do we distinguish between memories that are truly and lastingly toxic and those that, despite being unpleasant, helpe shape us into stronger, better, happier people — not just despite but because they sometimes make us feel bad. As Kandel has related elsewhere, the power of those memories from his ninth year helped drive his extraordinary 60-year (and counting) investigation of memory. As he puts it above, “It was horrible. But it shapes you.” In his case, they led to his work. His rough early memories helped make possible the very memory erasure that he now contemplates.

In the starkly lit world of bad movies, the line between ‘traumatic memory’ and helpful memory is brightly defined. In real life, good luck finding it. Bad memories have tremendous power to motivate change. They can imprison us — but they are just as likely to liberate us, driving us to change faults and habits that we might otherwise repeat. This can happen even with memories we’ve carried, to ill effect, for years.

A few memories, of course, are toxic and will always remain so. But I think those are a very few. When we try to distinguish between them and the rest, we enter a slippery slope obscured by the fog generated by our confusion, our amply demonstrated exaggeration of the power of drugs and technology, and our wishful thinking. I have thin faith we’ll walk that slope without falling.